Semiconductor device and fabrication method thereof

ABSTRACT

A semiconductor device includes a substrate having a fin structure extending along a first direction. The fin structure protrudes from a top surface of a trench isolation region and has a first height. A plurality of gate lines including a first gate line and a second gate line extend along a second direction and striding across the fin structure. The first gate line has a discontinuity directly above a gate cut region. The second gate line is disposed in proximity to a dummy fin region, and does not overlap with the dummy fin region. The fin structure has a second height within the dummy fin region, and the second height is smaller than the first height.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of Taiwan patent application No. 106134510, filed on Oct. 6, 2017, the disclosure of which is incorporated herein in its entirety by reference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to the field of semiconductor technology, and in particular to a FinFET semiconductor device and a method for fabricating the same.

2. Description of the Prior Art

In recent years, due to the miniaturization of various consumer electronic products, the size of the semiconductor devices must be minimized to meet the high degree of integration, high performance, low power consumption and a variety of product requirements. However, with the miniaturization of electronic products, the existing planar field effect transistor (planar FET) has been gradually filed to meet the requirements of the product. Thus, non-planar field-effect transistors such as fin-type field effect transistors (FinFETs) have been developed in the art to achieve high drive currents and to alleviate short channel effects.

It is known that the FinFETs can be fabricated using a slot-cut first process in which a cut-off region of a poly line is pre-formed in a polysilicon layer overlying the fin structure, and then the lithography process and etching process are performed to pattern the polysilicon layer to thereby form the poly line. However, the prior art slot-cut first process results in a loading effect when coating the organic dielectric layer (ODL), which affects the yield of the process. Therefore, there is still a need for an improved manufacturing method in this field.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide an improved semiconductor device and a method for fabricating the same, which can solve the disadvantages and shortcomings of the prior art.

According to one aspect of the invention, a method for fabricating a semiconductor device is disclosed. A substrate having thereon a trench isolation region and a plurality of fin structures extending along a first direction is provided. The plurality of fin structures protrude from a top surface of the trench isolation region. A polysilicon layer is deposited over the substrate. A poly cut opening and a dummy opening are formed in the polysilicon layer. An organic dielectric layer (ODL) is coated over the substrate. The ODL fills into the poly cut opening and the dummy opening. A hard mask layer is deposited on the ODL. A plurality of photoresist line patterns comprising a first photoresist line pattern and a second photoresist line pattern are formed. The photoresist line patterns extend along a second direction on the hard mask layer. The first photoresist line pattern overlaps with the poly cut opening. The second photoresist line pattern is disposed in proximity to the dummy opening, and does not overlap with the dummy opening. The photoresist line patterns are transferred to the polysilicon layer, thereby forming a plurality of poly lines extending along the second direction.

According to another aspect of the invention, a semiconductor device includes a substrate having a fin structure extending along a first direction. The fin structure protrudes from a top surface of a trench isolation region and has a first height. A plurality of gate lines including a first gate line and a second gate line extend along a second direction and striding across the fin structure. The first gate line has a discontinuity directly above a gate cut region. The second gate line is disposed in proximity to a dummy fin region, and does not overlap with the dummy fin region. The fin structure has a second height within the dummy fin region, and the second height is smaller than the first height.

These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic top view showing a semiconductor substrate after the formation of fin structures and after the blanket deposition of a polysilicon layer according to one embodiment of the invention.

FIG. 1B is a schematic, cross-sectional view taken along line I-I′ in FIG. 1A.

FIG. 2A is a schematic top view showing a semiconductor substrate after the formation of a poly cut opening and dummy openings in the polysilicon layer according to one embodiment of the invention.

FIG. 2B is a schematic, cross-sectional view taken along line I-I′ in FIG. 2A.

FIG. 3A is a schematic top view showing a semiconductor substrate after the formation of photoresist line patterns according to one embodiment of the invention.

FIG. 3B is a schematic, cross-sectional view taken along line I-I′ in FIG. 3A.

FIG. 4A is a schematic top view showing a semiconductor substrate after the transferring the photoresist line patterns to the underlying polysilicon layer according to one embodiment of the invention.

FIG. 4B is a schematic, cross-sectional view taken along line I-I′ in FIG. 4A.

FIG. 5A is a schematic top view showing a semiconductor substrate after the replacement metal gate (RMG) process according to one embodiment of the invention.

FIG. 5B is a schematic, cross-sectional view taken along line I-I′ in FIG. 5A.

DETAILED DESCRIPTION

In the following detailed description of the disclosure, reference is made to the accompanying drawings, which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.

The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. One or more implementations of the present invention will now be described with reference to the attached drawings, wherein like reference numerals are used to refer to like elements throughout, and wherein the illustrated structures are not necessarily drawn to scale.

Please refer FIG. 1A and FIG. 1B. FIG. 1A is a schematic top view showing a semiconductor substrate after the formation of fin structures and after the blanket deposition of a polysilicon layer according to one embodiment of the invention. FIG. 1B is a schematic, cross-sectional view taken along line I-I′ in FIG. 1A.

According to an embodiment of the present invention, the present invention discloses a method of fabricating a semiconductor device 1, for example, the semiconductor device 1 may be a fin-type semiconductor device or a FinFET semiconductor device, but is not limited thereto. First, a trench isolation region 102 and a plurality of fin structures 110 are formed on a substrate 100. According to an embodiment of the present invention, the substrate 100 may be a semiconductor substrate, such as a silicon substrate, but is not limited thereto. The fin structures 110 extend along a first direction (i.e., reference x-axis direction). The fin structures 110 protrude from a top surface 102 a of the trench isolation region 102.

As shown in FIG. 1A, the fin structures 110 form the dense pattern area 11. On the substrate 100, there may be a non-dense region 12 in which only the trench isolation region 102 is formed in the non-dense region 12 and no fin structure 110 is formed within the non-dense region 12.

According to an embodiment of the present invention, the dense pattern area 11 includes a dummy fin region 11 a adjacent to the non-dense region 12. According to an embodiment of the present invention, any circuit element, such as a transistor, a doped region, or a contact element, is not formed on the fin structure 110 of the dummy fin region 11 a. According to an embodiment of the present invention, a gate cut region 12 a is provided in the non-dense region 12. The gate cut region 12 a may completely overlap the trench isolation region 102 without overlapping the fin structures 110, but is not limited thereto.

According to an embodiment of the present invention, a polysilicon layer 200 is deposited on the substrate 100 in a blanket manner. The polysilicon layer 200 covers the plurality of fin structures 110 within the dense pattern area 11 and the trench isolation region 102 within the non-dense region 12. As can be seen from FIG. 1B, the fin structure 110 protrudes from the top surface 102 a of the trench isolation region 102 and has a first height h₁. A step height is formed at the interface between the dense pattern region 11 and the non-dense region 12.

Please refer FIG. 2A and FIG. 2B. FIG. 2A is a schematic top view showing a semiconductor substrate after the formation of a poly cut opening and dummy openings in the polysilicon layer according to one embodiment of the invention. FIG. 2B is a schematic, cross-sectional view taken along line I-I′ in FIG. 2A.

As shown in FIGS. 2A and 2B, a poly cut opening PO, a dummy opening DO1 and a dummy opening DO2 are formed in the polysilicon layer 200. The poly cut opening PO, dummy openings DO1 and dummy openings DO2 may be formed by using the same lithography process and etching process.

According to an embodiment of the present invention, the dummy opening DO1 is located directly on the dummy fin region 11 a and the dummy opening DO1 exposes the fin structures 110 within the dummy fin region 11 a. The poly cut opening PO is directly located on the gate cut region 12 a and is completely overlapped with the gate cut region 12 a. The dummy opening DO2 is adjacent to the poly cut opening PO and is located directly on the trench isolation region 102.

According to an embodiment of the present invention, portions of the fin structures 110 within the dummy fin region 11 a may be further etched away via the dummy opening DO1 such that the fin structures 110 has a second height h₂ in the dummy fin region 11 a, and the second height h₂ is smaller than the first height h₁.

In addition, the method of the present invention further includes recess etching the trench isolation region 102 via the poly cut opening PO and the dummy opening DO2, thereby forming a recessed structure 102 b on the trench isolation region 102 within the gate cut region 12 a and the dummy opening DO2.

According to an embodiment of the present invention, the top surface 110 a of the fin structure 110 within the dummy fin region 11 a is still higher than the top surface 102 a of the trench isolation region 102.

Please refer FIG. 3A and FIG. 3B. FIG. 3A is a schematic top view showing a semiconductor substrate after the formation of photoresist line patterns according to one embodiment of the invention. FIG. 3B is a schematic, cross-sectional view taken along line I-I′ in FIG. 3A.

As shown in FIGS. 3A and 3B, after the poly cut opening PO, the dummy opening DO1 and the dummy opening DO2 are formed in the polysilicon layer 200, an organic dielectric layer (ODL) 301 is deposited on the substrate 100. The poly cut opening PO and the dummy openings DO1 and DO2 are filled with the ODL 301. Next, a bottom anti-reflective layer 302 may be formed on the ODL 301. Then, a hard mask layer 303 may be deposited on the bottom anti-reflective layer 302, for example, a silicon nitride layer.

Subsequently, a plurality of photoresist line patterns 310 are formed on the hard mask layer 303, which includes a first photoresist line pattern 310 a and a second photoresist line pattern 310 b extending in a second direction (i.e., a reference y-axis direction), wherein the first photoresist line pattern 310 a overlaps the poly cut opening PO, and the second photoresist line pattern 310 b is adjacent to the dummy opening DO1 and does not overlap with the dummy opening DO1. According to an embodiment of the present invention, the plurality of photoresist line patterns 310 are not overlapped with the dummy opening DO1 or the dummy opening DO2.

Please refer FIG. 4A and FIG. 4B. FIG. 4A is a schematic top view showing a semiconductor substrate after the transferring the photoresist line patterns to the underlying polysilicon layer according to one embodiment of the invention. FIG. 4B is a schematic, cross-sectional view taken along line I-I′ in FIG. 4A.

As shown in FIG. 4A and FIG. 4B, the photoresist line patterns 310 are transferred to the polysilicon layer 200, thereby forming a plurality of poly lines 210 extending in the second direction. The poly lines 210 include a first poly line 210 a corresponding to the first photoresist line pattern 310 a, wherein the first poly line 210 a is cut off or intersected by the poly cut opening PO.

According to an embodiment of the present invention, the poly lines 210 further comprise a second poly line 210 b corresponding to the second photoresist line pattern 310 b, wherein the second poly line 210 b does not overlap the dummy fin region 11 a.

According to an embodiment of the present invention, a source/drain contact region 410 is provided between the second poly line 210 b and the dummy fin region 11 a.

Please refer FIG. 5A and FIG. 5B. FIG. 5A is a schematic top view showing a semiconductor substrate after the replacement metal gate (RMG) process according to one embodiment of the invention. FIG. 5B is a schematic, cross-sectional view taken along line I-I′ in FIG. 5A.

As shown in FIGS. 5A and 5B, a dielectric layer 501 is formed on the substrate 100 and planarized. Then, the plurality of poly lines 210 are replaced with a plurality of metal gate lines 510 including a first gate line 510 a and a second gate line 510 b extending in the second direction and across the fin structures 110 by a replacement metal gate (RMG) process, where the first gate line 510 a is discontinuous in the gate cut region 12 a and the second gate line 510 b is adjacent to the dummy fin region 11 a and does not overlap the dummy fin region 11 a.

Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims. 

What is claimed is:
 1. A method for fabricating a semiconductor device, comprising: providing a substrate having thereon a trench isolation region and a plurality of fin structures extending along a first direction, wherein the plurality of fin structures protrude from a top surface of the trench isolation region; blanket depositing a polysilicon layer over the substrate; forming a poly cut opening and a dummy opening in the polysilicon layer; blanket coating an organic dielectric layer (ODL) over the substrate, wherein the ODL fills into the poly cut opening and the dummy opening; blanket depositing a hard mask layer on the ODL; forming a plurality of photoresist line patterns comprising a first photoresist line pattern and a second photoresist line pattern extending along a second direction on the hard mask layer, wherein the first photoresist line pattern overlaps with the poly cut opening, and the second photoresist line pattern is disposed in proximity to the dummy opening, and does not overlap with the dummy opening; and transferring the plurality of photoresist line patterns to the polysilicon layer, thereby forming a plurality of poly lines extending along the second direction.
 2. The method according to claim 1 further comprising: forming a bottom anti-reflection coating (BARC) layer on the ODL before blanket depositing the hard mask layer.
 3. The method according to claim 1, wherein the plurality of poly lines comprises a first poly line corresponding to the first photoresist line pattern, and wherein the first poly line is segmented by the poly cut opening.
 4. The method according to claim 3, wherein the dummy opening is formed directly on a dummy fin region, and wherein the plurality of poly lines comprises a second poly line corresponding to the second photoresist line pattern, and wherein the second poly line does not overlap with the dummy fin region.
 5. The method according to claim 4, wherein a source/drain contact region is disposed between the second poly line and the dummy fin region.
 6. The method according to claim 1, wherein portions of the plurality of fin structures are removed from the dummy opening.
 7. The method according to claim 6, wherein the plurality of photoresist line patterns do not overlap with the dummy opening.
 8. The method according to claim 1, wherein the poly cut opening is completely overlapped with the trench isolation region and does not overlap with any of the plurality of fin structures.
 9. The method according to claim 8 further comprising: recessing the trench isolation region through the poly cut opening. 